"Is Gaia worth the $19.99 price when there other cheaper or "free" alternatives? I've tried many, but have not been satisfied."
I don't regret the purchase. I purchased the Gaia ap last winter and I've only had a few opportunities to use it. It's slower once I'm off the grid but I expected that.
I'm also a map/compass sort of guy and I was looking for something which would allow for me to plot the occasional grid when my dead reckoning has turned into reckoning (e.g. reckon we're over here or reckon we're over there?) I participated in a land nav course a few weeks ago. An instructor and I played with it and compared the accuracy to the map and to a garmin GPS. Gaia was spot on.
To me, $20 for an iphone ap was a cheaper option from a weight and cost perspective than buying a standalone GPS system. It seems to work fine but I've found that it (like any other GPS) requires some practice before taking it to the field. For someone who wants a GPS to track their movement, etc then obviously a phone battery will not be able to support that level of processing for very long.
I use an iPhone 4s so I'm not sure how well it would work with a 3GS. To be honest, I didn't realize that he iphone could work as a GPS off the grid until about a year ago.